As permitted CO2 exhaust gas emission values in the automotive sector become more stringent, it is desirable to develop new technologies for improving overall efficiency of a reciprocating-piston internal combustion engine. Such technology relates, for example, to variable setting of a cylinder compression of gas in cylinders of the internal combustion engine, in order to achieve optimal operation of the internal combustion engine without knock susceptibility and with individually settable cylinder compression for different engine operating points. Variable cylinder compression also influences the fuel consumption of the internal combustion engine and the exhaust gas emissions of the internal combustion engine. Prerequisites for this are that an internal combustion engine with variable cylinder compression be diagnosis-relevant in accordance with current onboard diagnosis legislation, and that implementation of the setting of cylinder compression for the internal combustion engine must be monitored during engine operation for correct functionality. DE 199 55 250 A1 discloses such functional monitoring of variable cylinder compression in a reciprocating-piston internal combustion engine, which evaluates rough running, combustion chamber pressure, intake duct pressure, or engine torque of the internal combustion engine for functional monitoring.
It is desirable to furnish mechanisms for functional monitoring of a variable cylinder compression setting in a reciprocating-piston internal combustion engine which are particularly easily implementable, accurate, and efficient.